The nonlinearities of a nonlinear system can degrade the performance of a closed-loop system. In order to improve the performance of the closed-loop system, an adaptive technique, using a neural network, was developed. A neural network is placed in series between the output of the fixed-gain controller and the input into the plant. The weights are initialized to values that result in a unity gain across the neural network, which is referred to as a "feed-through neural network." The initial unity gain causes the output of the neural network to be equal to the input of neural network at the beginning of the convergence process. The result is that the closed-loop system's performance with the neural network is, initially, equal to the closed-loop system's performance without the neural network. As the weights of the neural network converge, the performance of the system improves. However, the back propagation algorithm was developed to update the weights of the feed-forward neural network in the open loop. Although the back propagation algorithm converged the weights in the closed loop, it worked very slowly. Two new update algorithms were developed for converging the weights of the neural network inside the closed-loop. The first algorithm was developed to make the convergence process independent of the plants dynamics and to correct for the effects of the closed loop. The second algorithm does not eliminate the effects of the plant's dynamics, but still does correct for the effects of the closed loop. Both algorithms are effective in converging the weights much faster than the back propagation algorithm. All of the update algorithms have been shown to work effectively on stable and unstable nonlinear plants. / Ph. D.

This study explores the relationship between an individual's current professional occupation and the effect of the order of information on their evaluation when making internal control effectiveness judgments. The Sarbanes-Oxley Act (SOX) requires a new mindset for individuals that have responsibility for the internal controls in place at an organization. SOX requires both auditors and management to evaluate the effectiveness of the internal controls over financial reporting. Prior to the implementation of SOX, auditors were required to evaluate internal controls and their effect on the reliability of the financial statements; however, neither group was required to provide an opinion to the public regarding the findings of the evaluation. This study utilizes a within- and between-subjects research design, using the subjects' occupation (auditor or management) as one independent variable, and manipulating the order in which the cases are received by the subjects for the second independent variable. For each case, the subjects were provided three internal control judgments: effectiveness and efficiency of operations, reliability of financial reporting, and Sarbanes-Oxley required internal control effectiveness judgment. Additionally, subjects indicated their reliance on each of the internal control effectiveness cues included by allocating 100 points among each of the six cues included in the instrument. Based on the results of the current study, auditors and management did not provide different judgments. Additional analyses were conducted to explore whether experience impacts the self-insight individuals have into their reliance on cues when providing judgments. Findings did not indicate that subjects with greater experience were more likely to have greater insight into their reliance on information. The findings suggest that neither role nor case ordering affected the subjects' professional judgment. Overall, auditors and management did not provide statistically significant different judgments in relation to Sarbanes-Oxley judgments. The similarity in judgments should provide some reassurance to auditors and investors that given no guidance but the same information for judgments, management and auditors will come to similar conclusions regarding the effectiveness of internal controls over financial reporting. / Ph. D.

by Liu Chi-wah, Peter. / Bibliography: leaves [142]-148 / Thesis (M.Ph.)--Chinese University of Hong Kong, 1984

Wong Pak Kai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1989. / Bibliography: leaves [59-61]

Small businesses have an important role to play in the U.S. economy. However, employee fraud can jeopardize the sustainability of small businesses. Grounded on Cressey's fraud triangle theory, the purpose of this multiple case study was to explore strategies used by selected managers and owners of small retail businesses to detect and prevent employee fraud. Ten participants from 5 small retail businesses participated in the study. Nine participated in a face-to-face semistructured interview, and 1 participated in a telephone interview. These participants included 5 owners and 5 managers of small retail businesses in the state of Michigan in the United States who have implemented strategies to detect and prevent employee fraud. Through a process of methodological triangulation, casual observations and documentary evidence supplemented data collected through semistructured interviews. Using thematic analysis by coding narrative segments, the research findings included themes of controls and communication, cash register accountability, segregation of duties, monitoring, and action against perpetrators. Managers and owners of small businesses may benefit from the findings of this study by gaining awareness of the need to detect and prevent employee fraud. The implications for positive social change may include the potential to increase appropriate controls over employee fraud, thus enabling owners of small retail business an opportunity to operate effectively and efficiently, which could increase employment opportunities. Increased employment opportunities could create a positive effect on other small retail businesses and allow local communities to prosper.

We present new adaptive control algorithms that address the problem of rejecting sinusoids with known frequencies that act on an unknown asymptotically stable linear time-invariant system. To achieve asymptotic disturbance rejection, adaptive control algorithms of this dissertation rely on limited or no system model information. These algorithms are developed in discrete time, meaning that the control computations use sampled-data measurements. We demonstrate the effectiveness of algorithms via analysis, numerical simulations, and experimental testings. We also present extensions to these algorithms that address systems with decentralized control architecture and systems subject to disturbances with unknown frequencies.

Not available / text

published_or_final_version / Public Administration / Master / Master of Public Administration

This thesis presents rules that characterize the root locus for polynomials that are nonlinear in the root-locus parameter k. Classical root locus applies to polynomials that are affine in k. In contrast, this thesis considers polynomials that are quadratic or cubic in k. In particular, we focus on constructing the root locus for linear feedback control systems, where the closed-loop denominator polynomial is quadratic or cubic in k. First, we present quadratic root-locus rules for a controller class that yields a closed-loop denominator polynomial that is quadratic in k. Next, we develop cubic root-locus rules for a controller class that yields a closed-loop denominator polynomial that is cubic in k. Finally, we extend the quadratic root-locus rules to accommodate a larger class of controllers. We also provide controller design examples to demonstrate the quadratic and cubic root locus. For example, we show that the triple integrator can be high-gain stabilized using a controller that yields a closed-loop denominator polynomial that is quadratic in k. Similarly, we show that the quadruple integrator can be high-gain stabilized using a controller that yields a closed-loop denominator polynomial that is cubic in k.

Licentiatavhandling (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2006. / Härtill 2 uppsatser.